LAUSR

Abstract We created a Mg/steel butt-welded plate by hybrid laser-tungsten inert gas double-sided welding with a Ni interlayer. The tensile strength of the Mg/steel butt-welded plate reached 232 MPa, which was about 90.6% of the Mg alloy base metal (256 MPa). Uniform nanoparticles of the AlNi phase formed and then dispersed in the weld seam, which is conducive to improving its strength. The steel at the Mg/steel interface melted and formed an arc transition zone. The transition zone between the weld seam and the steel base metal was composed of a Mg/steel interface layer (1 μm wide) and Fe-Ni solid solution (60–500 μm wide), and we also found Al elements enriched in the Mg/steel interface. The addition of a Ni interlayer was found to significantly improve the weldability and also played a synergistic strengthening role on the weld seam and Mg/steel interface.